Database Reference
In-Depth Information
F
IGURE
9.2
The Inventory submodel from the Mountain View Music logical model
As we work toward our physical model, we will go through each of our
submodels one at a time. In this way, we can take small sections and build
the physical model in a logical manner rather than try to look at the entire
model at the same time.
In addition, as we go through, we will see that certain entities, such as
Employees, exist in multiple submodels. We will deal with these entities in
the model that they truly belong to. In other words, entities such as List
Items appear for lookup purposes in many of our submodels; however, be-
cause there is an entire submodel dedicated to lists, we will ignore the List
Items entity until we get to the Lists submodel. For this first pass, we con-
cern ourselves only with getting entities from our logical model and find-
ing a place for them in our physical model; we deal with columns and
relationships in the next section.
Products Submodel
The first submodel we need to work with for our physical database
contains the entities relating to the company's products. This submodel
is shown in Figure 9.3, and the entities we will be working with are as
follows:
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